The present invention relates to a panel antenna. More particularly, but not exclusively, the present invention relates to a panel antenna having both mechanical and electrical means for tilting the beam of the antenna. The antenna of the present invention is considered to be particularly suitable for use in cellular communication systems.
To the present time downward tilting of the beam of an antenna used in a cellular communication system has been achieved by mounting the panel antenna at an angle to the supporting structure. Where panel antennas are to be affixed to the sides of buildings it is preferable that the panel antennas conform as closely as possible with the sides of the buildings for aesthetic reasons and to avoid exposing too great a surface area to the wind. Where conventional mounting arrangements are used a panel may be tilted by as much as 15.degree. with respect to a building, which is unsightly, poses mounting difficulties and exposes the panel to the full impact of the wind. Likewise with panel antennas mounted on towers it is more asthetically pleasing, and the antennas are easier to mount and adjust if they are mounted perpendicularly.
Another method of downwardly tilting the beam of a panel antenna is to electronically phase shift the signal received by or transmitted from each dipole pair an amount corresponding with the desired degree of beam tilt. As the amount of downward tilt required for each site varies (depending upon the height of the base-station etc) this would require the use of variable phase shifting elements which would be expensive.
It is an object of the present invention to provide a panel antenna allowing customer adjustable beam down tilt which is relatively cheap and simple whilst being easily mounted and aesthetically pleasing, or to at least provide the public with a useful choice.